Electrical generators utilized in the power generation industry include a rotor and a winding. Referring to FIG. 1, a partial view of a rotor 10 is shown which is configured for rotation about a longitudinal axis 12. The rotor 10 includes a substantially cylindrically shaped rotor body 14 and two rotor shaft extensions 16, which extend axially from the rotor body 14 along the longitudinal axis 12. An outer periphery of the rotor body 14 includes a plurality of axially extending slots 18, which extend the complete length of the rotor body 14. The rotor 10 also includes a winding 20, which includes a plurality of straight axial sections 22 each connected to an associated arc shaped end turn or end arc section 24 that is oriented transverse to its associated straight section 22. A plurality of straight sections 22 is located in each slot 18 such that the straight sections 22 and the end arc sections 24 form a stacked or layered arrangement. The straight sections 22 and associated end arc sections 24 are each fabricated from copper.
In many generators currently in use, each straight section 22 is affixed to an associated end arc section 24 by a weld joint known as a square corner braze joint. Referring to FIG. 2, a square corner braze joint 26 is shown. A square corner braze joint 26 is the location at which a straight section 22 is brazed to a side of an end arc section 24 to form a braze joint 28. The straight section 22 and end arc section 24 form a sharp corner 29 that coincides with the braze joint 28. In addition, a braze filler material used to form the braze joint 28 forms a radius 30 at the corner 29. Square corner braze joints 26 were first implemented as a cost reduction measure and have been commonplace for many years. Further, square corner braze joints 26 were implemented as part of a change away from a bent end arc design in order to provide a higher rating due to improved cooling and increased cross section size of the end arc.
An alternative end arc configuration is shown in FIG. 3. FIG. 3 shows a plurality of end arcs 32 known as bent end arcs 32. In this configuration, the straight sections 22 of the winding 20 are made longer and then bent at a predetermined angle at first locations 33. A braze joint 34 is then formed between left 35 and right 36 halves of the winding 20 in a center of each bent end arc 32. However, conversion of a square corner braze joint 26 to a bent end arc 32 configuration has drawbacks. At the outset, substantially all of the straight sections 22 and the end arc sections 24 in an existing rotor 10 would have to be replaced. In addition, new rotor ventilation and insulation schemes must be designed and manufactured. Further, manufacturing is more complicated since the straight sections must be worked into intricate geometries. Another drawback is that the upgraded cooling designs of the end arc such as providing larger cross sections with or without intercooled end arcs cannot be manufactured using a bent end arc design.